Modeling Glass Tips and Tricks
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Every month I'll be writing about how to use Modeling Glass in your work, and hopefully answering some questions that will help you get the results you want. There's always a learning curve with a new product, and there are considerations working with frit and powder that you don't have when firing sheet glass.
There is a full set of FAQs on the Modeling Glass website at
www.modelingglass.com
. You can also find back issues of all my e-newsletters there!
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Now Available!
Exploring Modeling Glass: Making A Mask
A New Video From
AAE Glass
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In this video, I cover tools, mixing, managing colors at different temperatures, controlling shrinkage, working with components, and much more. It's a great primer for how to make 3-dimensional shapes with Modeling Glass. It also features a NEW draping form I designed myself, which is being fabricated by Creative Paradise, but is currently ONLY available through AAE Glass. I'm thrilled to be able to contribute another new tool for glass artists to use. You can learn more about the video and order the draping form
here
.
I hope you'll check it out, and thank you for being part of the MG crew!
SPECIAL OFFER FROM AAE GLASS:
AAE is doing a giveaway of 10,000 education coins to one lucky person who reviews a video or item at
aaeglass.com
No purchase necessary. Every review you do equals one entry, no limit. Please review my mask video or feather video. CONTEST ENDS FEBRUARY 18!
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This mask draping form was designed from my original prototype and produced by the great folks at Creative Paradise just for this video project! It's available exclusively through AAE Glass. Order yours
HERE
today!
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COMPARING LEAVES FIRED AT TWO DIFFERENT TEMPERATURES:
At left: these leaves were cut out of sheet of Modeling Glass that was made from multiple colors all rolled together then cut out with cookie cutters.
The five leaves on the left side were then fired to 1275 degrees F as the process temperature with a 10-minute hold. The five leaves on the right were fired at 1325 degrees F with a 30-minute hold.
The leaves on the left are matte in finish, with a lot of textural detail. The leaves on the right are glossy, and have slightly less texture and more rounded edges.
The leaves on the right are also brighter in color, and slightly smaller due to the additional shrinkage that happens at a hotter temperature.
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HEAT AND COLOR IN MODELING GLASS
I've had several inquiries from new users of Modeling Glass asking about color...the most common question is, "why does my fired Modeling Glass piece look kind of grey, instead of the bright color I expected?"
There are multiple factors that influence the end result of a fired piece of Modeling Glass (MG). First I'll tell you what is NOT causing the color shift: there is no residual uncombusted binder or liquid medium affecting the color. All the ingredients of MG burn away by 900 degrees F, leaving behind just the glass powder. I have fired a piece to 900 and then crash cooled it just to see what happens. When I attempted to lift the cooled piece of MG out of the kiln, it crumbled to dust in my hands. When MG is taken to full fuse, the colors are completely true to what you expect. Now, on to what DOES affect color in MG:
TRAPPED AIR
Color is affected by trapped air in between the particles of powdered glass. This is an effect common to all pate de verre processes, and it is most apparent in MG because of the thickness of your piece, and the low peak temperature in my basic tack-fusing firing schedule. Because MG is a porous material, there's a lot of trapped air in it. When this air is driven out during firing, it results in about 15% shrinkage.
Bullseye Glass Company's excellent online video library (there's an annual fee but it's a great deal for such an extensive resource) contains a video titled "Heatwork and Frit." You can subscribe
here
.
Here's a quote from the video that perfectly describes what I'm talking about: “Another phenomenon that affects color and even opacity of ground glass when fired is the influence of air trapped within the material. Air between the grains of ground glass will be trapped in the form of very small bubbles within the fused piece. The effect becomes especially noticeable with transparent glasses. The bubbles trapped within the smaller grain sizes scatter the light in such a way as to make transparent glass appear more like an opalescent glass." This is also the reason why Modeling Glass made with transparent frit will not be transparent when fired. However, it will be slightly more translucent than a true opalescent powder.
FIRING TEMPERATURE AND HEATWORK
If you have an older Modeling Glass Starter Kit, you might have the instructions with only one suggested firing schedule. Since then, I have expanded the instructions to include an additional hotter schedule. You can download a PDF of the new instruction sheet
here.
The basic tack-fuse schedule only goes up to 1275 as the process temperature. This is just enough to sinter (melt) the particles together, drive out a lot of the air, and "pre-shrink" your shapes (MG has about 15% shrinkage at 1275 degrees F.)
The new schedule takes the MG up to 1325 with a 30-minute hold. I find that this additional amount of heat and time is enough to get the colors much brighter while still preserving most of the texture. The result will be glossier than the lower temperature, but your colors will be richer.
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PHOTO OF FRENCH VANILLA AND HEATWORK:
At right: these are the quills of two glass feathers. Each was made using Bullseye French Vanilla Opal powder. The top feather was fired to a peak temperature of 1275 degrees F. The bottom quill was also fired to 1275 degrees F, but it went through four firings.
The French Vanilla quill on top has a slightly grayish cast, while the bottom quill is much more true creamy white and it is also glossier. This shows how cumulative heatwork can mature colors, especially light colors.
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STRIKER COLORS
Another factor is what colors you are using, and whether they need higher temperatures to mature to their true colors or "strike." I have had questions from folks using Petal Pink, Gold Purple Opal, Yellow, and other colors that just don't fire true at 1275 degrees F. For instance, at this tack-fuse temperature there can be a distinct greenish tint to yellow glass. Fortunately, the solution is easy: just re-fire the piece hotter! The additional heatwork will mature the colors.
RESIDUAL MOISTURE
In the instruction sheet, I recommend drying all Modeling Glass shapes thoroughly before firing, at 200 degrees F for at least 30-60 minutes depending on the thickness and size of the shape. I often have to dry larger shapes for a couple of hours. Driving out any residual moisture in the MG piece is essential to it firing properly. If you skip the drying step, or just air-dry the piece, there is still a chance that there will be residual moisture in the center, which will retard the firing. It's not the end of the world if you fire a piece that is still damp inside (it won't blow up or be ruined). But you will get a very grey result and then you'll just have to fire it all over again. Better just to make sure it's really dry. On really thick (1/4" or more) I will add a 3-hour 200-degree drying segment to the firing schedule just to be sure.
VARIATION BETWEEN KILNS
All kilns fire differently; it's not unusual to see variation even between two kilns of the same brand/size. A large kiln will typically result in more heatwork because all that thermal mass takes longer to heat up and longer to drop down from peak temperature. I've seen large, older kilns in which I've had to alter my firing schedule downward by 100 degrees to get the same result I would have in my Paragon Benchtop16 that's 5 years old. If you are getting consistently underfed/grey MG out of your firings, your kiln probably runs cool, so adjust your schedule accordingly. If your pieces are coming out too smooth/glossy, then your kiln runs hot. MG is more sensitive to slight temperature variations than sheet glass; even 25 degrees can make a noticeable difference in the result.
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These are the biggest factors to consider when trying for bright colors and maximum texture. I talked about the maturation of white in my
March 2019 eNews
, so that is another good discussion about heat and color. My upcoming Ebook will have more examples and information about heat and getting the most out of your Modeling Glass projects.
RIGHT: Three petals of Opaque White Opal fired with 3 different schedules...read the March 2019 eNews for more info.
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This year's workshops will feature a different feather than 2019, but that's not all you'll learn! We do several projects that help you stretch your imagination and get a grasp of the many ways you can incorporate Modeling Glass into your artwork. Here is a list of where I'll be teaching and when:
March 13-15 Albuquerque, NM at Hot Flash Glass
April 4 Demo Day at Las Vegas Glass Craft and Bead Expo at D&L Glass Booth
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May 15-17 Old Hickory, TN at This Little Light Art Glass
June 4-6 Frederick, MD at Anything in Stained Glass
August 7-9 Ottawa, Canada at Glass eMotions
August 13-16 Madison Wisconsin at The Vinery Glass Experience
September 16-18 Denver, CO at D&L Art Glass
October 23-25 Phoenix, AZ at Milkweed Arts
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Modeling Glass
This new product was developed by Lois Manno of Glass Bird Studios. It is a two-part system made of a powdered binder and liquid medium that, mixed with frit or powders along with a little water, turns the powder into a material that can be sculpted like clay. It is featured in the workshops she teaches.
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Want to purchase Modeling Glass? A list of retailers is available on the website. The list keeps growing, so check back. Ask your glass retailer to add Modeling Glass to their stock if they don't have it!
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Dear glass artist: you're receiving this message because you have expressed interest in Modeling Glass or Glass Bird Studios. If you would like to continue receiving occasional emails about Modeling glass, workshops, and user tips, there is no action for you to take. If you wish to unsubscribe from the list, you can do so at the bottom of this message. Thanks for your interest in Modeling Glass!
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